Reefer vs dry container: what the insulation costs

A reefer loses about 444 mm of inside length, 60 mm of width and 122–154 mm of height to insulation and the cooling unit: 4.9 m³ in a 20ft box and 9.0 m³ in a 40ft high cube. Pallet losses range from none to more than half: the 48×40 keeps all its places in the high cube reefer, while the Australian square pallet drops from 20 to 9.

By Oliver Bennett · Published 29 October 2026 · Data as of 27 October 2026, from spec sheets retrieved that day

A reefer is a dry box lined with insulation and fitted with a refrigeration unit at the front end. From the outside the two look the same size; ISO gives them identical external dimensions. Everything the reefer adds comes out of the cargo space and the payload.

Side by side

Where the space goes

The length loss is nearly identical in both sizes: 444 mm in the 20ft and 445 mm in the 40ft high cube. That points to a fixed cost, the refrigeration unit and the insulated front wall, rather than something that grows with the box. Width shrinks by 60 mm and 63 mm, the two side walls' worth of insulation. Height drops by 122 mm and 154 mm, which includes the insulated roof and the raised floor gratings that let cold air circulate underneath the cargo.

In volume the 20ft reefer gives up 4.9 m³ and the high cube reefer 9.0 m³. Because the loss is mostly fixed, the small box suffers more in proportion: 14.8% of the 20ft dry volume against 11.8% of the high cube's.

Weight: the high cube reefer carries more

The reefer box is heavier, by 660 kg in the 20ft and 730 kg in the high cube. In the 20ft size the gross rating is the same as the dry box, so the heavier box simply means 660 kg less payload.

The high cube reefer goes the other way. Its typical gross rating is 34,500 kg against 32,500 kg for the dry high cube, and that more than pays for the extra steel: its typical payload is 800 kg higher than the dry box's. Ratings vary by owner, and the full list of weights is in container weights.

Pallets lost to the insulation

The table shows the best single-layer count in each dry box and in its reefer twin, for every pallet standard.

In the 20ft size the reefer keeps the dry count for four of the 11 pallets and loses up to six for the rest. The EUR1 drops from 11 to 10. In the 40ft high cube size three pallets keep their count, among them the 48×40: its 1,016 mm width goes twice into the reefer's 2,280 mm with room to spare, so the narrower walls cost nothing.

The square Australian pallet is the casualty. Two of them side by side need 2,330 mm, more than either reefer offers, so only one fits across the floor. It falls from 10 to 4 in the 20ft and from 20 to 9 in the high cube, the largest losses in the data.

Height for a second layer

On the smallest published inside heights, the dry high cube offers 2,695 mm and the reefer 2,537 mm. Two layers of pallets fit in the dry box while each unit stays under 1,347 mm, and in the reefer under 1,268 mm. Units between those heights stack in one and not the other. In the 20ft size neither box takes two layers of 1,200 mm units.

Check a reefer against your own pallet and unit height in the load planner, or read the full pages for the 20ft reefer and the 40ft high cube reefer.

More guides: 20ft vs 40ft vs 40ft high cube containers · Shipping container door dimensions · Container weights: tare, payload and max gross · Open top vs flat rack vs platform containers · 45ft high cube vs 45ft pallet-wide container · UK pallet vs Euro pallet: 1200×1000 against 1200×800 · Square pallets in containers and trailers · All guides